1. Field of the Invention
The invention relates to a communication system with a control circuit the circuit comprising an operating system and user software and means for exchanging software.
2. Discussion of the Related Art
Communication systems comprise computer systems or control circuits hose software is to be durable and practically always available. In the event of errors in the software or also because of new requirements, certain software components are to be renewed. In that case the down-time of the communication system is to be minimized.
A communication system which has practically no down-time when software of a component of a switching system is to be exchanged is known from U.S. Pat. No. 5,155,837. Before the exchange, first the contents and states of all the registers, processors and memory units are saved in a special memory while the old software is being used (column 7, lines 30 to 36). The old version of the software is then loaded into a first partition. Subsequently, the new software is loaded into a second partition. After the new software has been loaded and tested, the contents and states of all the registers, processes and memory units in the memory are copied to the new software. This new software is then taken into operation. The new software, however, does not start operating at the point in the process where the old software was stopped, but at a defined program point. Neither are individual software modules or software components exchanged, but only software incorporated therein.